Optical luminescent display device

ABSTRACT

A luminescent material, such as phosphor, is radiated by energy propagated from the side of an optical fiber, causing the luminescent material to emit visible light The luminescent material can be of a coincidentally-excited type, requiring the absorption of two wavelengths of radiation to emit visible light. In such a case, two side-emitting optical fibers can be used, with each optical fiber providing one of the needed radiation wavelengths. One embodiment of the invention involves a matrix of optical fibers forming an optical display panel made using coincidentally-excited phosphors. Side-emitting optical fibers are used to simultaneously stimulate a phosphor pixel located between the two fibers, allowing matrix addressing of each pixel individually. The optical display panel is constructed of only optical components. Another embodiment involves an optical switch with coincidentally-excited luminescent material. One radiation is provided by a side-emitting optical fiber. To activate the switch, a second radiation is provided by a laser diode.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority from U.S.Provisional Patent Application Ser. No. 60/098,769, which isincorporated herein by reference in its entirety.

BACKGROUND Field of the Invention

[0002] The present invention relates generally to the use of aluminescent compound radiated by energy propagated from the side of anoptical fiber. One embodiment of the invention involves a display matrixmade from coincidentally-excited phosphors. Another embodiment involvesan optical switch.

[0003] Desktop computer monitors, laptop computers, televisions, and awide variety of electronic devices incorporate displays. These displaysare often of a cathode ray tube (CRT) or liquid crystal displayconstruction. An example of a liquid crystal display panel is describedby Funada, et al. in U.S. Pat. No. 4,231,640. The conventionalconstruction of displays has typically involved high-voltage componentsand the emission of electromagnetic radiation and electromagneticinterference (EMI) from the display panel. Size and weightcharacteristics of conventional displays often make portabilitydifficult or inconvenient. Also, durability of the display can betroublesome, due to the high number of electronic parts, or alignmentrequired of various components.

[0004] There is currently no display technology that can provide a verythin, light and durable display panel that produces no electromagneticinterference or noise. Even a phosphor-based display has typicallyinvolved a complex construction involving variety of transistors, pixeldrivers, electrodes and line or column electrical wire.

[0005] There are some display technologies that involve optical fibersadapted to emit visible light from the side of the optical fibers.However, these technologies are limited in that each optical fiber iseither “on” or “off,” causing an entire row of notches to emit thevisible light transmitted through the fiber simultaneously. Each row ofnotches is also limited to the same color of visible light transmittedthrough the common optical fiber. None of these technologies combineluminescent materials with side-emitting optical fibers.

[0006] U.S. Pat. No. 5,432,876 discloses an optical fiber having a lightemitting region to propagate light from an optical fiber in apreselected direction. One embodiment of '876 involves mounting ofoptical fibers to a panel so as to form a substantially parallel array.In one embodiment, a liquid crystal shutter array (LCS) is formed infront of the substantially parallel array so as to block unwanted notchemissions from view. However, '876 only teaches the redirection of lightfrom the notch of an optical fiber and not the illumination of aluminescent material.

[0007] U.S. Pat. No. 5,659,643 discloses a notched fiber arrayillumination device. '643 is similarly limited to only teaching theredirection of light from an optical fiber, but does teach a Fresnellens or other beam turning device can be used to further redirect lightemitted from the notch of an optical fiber.

SUMMARY

[0008] The present invention transmits radiation through a side-emittingoptical fiber to radiate a luminescent material and produce visiblelight. This allows for an optical luminescent display device to beconstructed without electronic components.

[0009] A second embodiment of the invention is an optical switch. Theoptical switch involves radiation provided from within a side emittingoptical fiber and, upon activation of the optical switch, a secondradiation provided by a laser diode or infrared LED.

[0010] Another embodiment of the invention involves a display panel madefrom a matrix of optical fibers capable of coincidentally-radiatingpixels of luminescent material. This allows for matrix-addressing ofindividual pixels within a display panel.

[0011] It is therefore an object of the invention to provide a displaypanel that is entirely optical, thereby providing a rugged device, ableto operate where electronic devices can not be used, including hightemperature environments.

[0012] It is a further object of the invention to provide a displaypanel that can be separate from the light source providing excitation.

[0013] It is a further object of the invention to provide a display withno high-voltage, no electromagnetic radiation and no EMI from thedisplay panel.

[0014] It is a further object of the invention to provide a matrix of aplurality of all-optical pixels, having no electronics in the displaypanel.

[0015] It is a further object of the invention to provide simpleconstruction of a display panel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing and other features, objects, and advantages of theinvention will be better understood by reading the following descriptionin conjunction with the drawings, in which:

[0017]FIG. 1 illustrates an optical luminescent display device ofoptical side-emitting fiber with luminescent material embedded in thenotch.

[0018]FIG. 2 shows the same optical luminescent display device of FIG.1, but using multiple IR wavelengths to stimulate visible RGB lights.

[0019]FIG. 3 shows the same optical luminescent display device of FIG.1, but using multiple UV wavelengths to stimulate visible RGB lights.

[0020]FIG. 4 is a scheme for multiple UV sources and multiple IR sourcesto address individual visible RGB light coincidentally (simultaneously).

[0021]FIG. 5 shows a luminescent material embedded in a notch in thepath of radiation within the optical fiber, thereby causing theluminescent material to emit visible light.

[0022]FIG. 6 shows an optical switch using luminescent material.

[0023]FIG. 7 shows an optical switch modulated by an IR laser diode orIR LED.

[0024]FIG. 8 is a perspective view of the cross section of twoside-emitting optical fibers with a luminescent material between thenotches.

[0025]FIG. 9 is a perspective view of the cross section of twoside-emitting optical fibers with a luminescent material coated in onenotch.

[0026]FIG. 10 shows a structure of triangular shaped notches forside-emitting radiation to a luminescent material.

[0027]FIG. 11 shows a structure, including a filter, of triangularshaped notches for side-emitting radiation to a luminescent material.

[0028]FIG. 12 shows a structure of inner side notches for charging anddischarging the phosphors.

[0029]FIG. 13 shows the structure of two side-emitting fibers with Vshape notches across from each other and sandwiching the phosphorbetween them for stimulating and addressing.

[0030]FIG. 14 shows the structure, including filters, of twoside-emitting fibers with V shape notches across from each other andsandwiching the phosphor between them for stimulating and addressing.

[0031]FIGS. 15 and 16 are exemplary patterns and pixel arrangements ofthe single-color addressable phosphors.

[0032]FIG. 17 illustrates a matrix addressing method for opticalphoto-stimulable phosphors with UV, IR or flash discharge sources andoptical beam scanning systems.

[0033]FIG. 18 shows a structure of matrix addressing with one back-sidedischarge lamp.

[0034]FIG. 19 shows an optical beam scan system for vertical or columnscanning using a discharge lamp through an optical beam splitter to awhole fiber array or bundle. The mechanically rotated mirror oracoustics crystal device is suitable for an optical beam switch.

[0035]FIGS. 20A, 20B and 20C illustrate the coupling approach foroptical power sources with an optical fiber bundle. The linear laserarray is directly coupled to a linear fiber array and an optical beamswitch device providing the switching function between the rows.

[0036]FIGS. 21 and 22 are examples of time charts for a matrix scanningsystem.

[0037] FIGS. 23-25 are progressively closer perspective views showingthe intersection of optical fibers to form an optical display panel.

[0038]FIG. 26 is a perspective view of the structure of a scanningoptical fiber matrix with detailed structural elements omitted forclarity.

DETAILED DESCRIPTION

[0039] The various features of the invention will now be described withrespect to the figures, in which like parts are identified with the samereference characters.

[0040] The structure shown in FIG. 1 will now be described. The opticalluminescent display device 30 is comprised of an optical fiber 32 thatincludes a notch 34. The optical fiber 32 is made of an opticallytransmissive substance, such as plastic or glass. Virtually any diameterof optical fiber 32 can be used. If glass optical fiber is used, adiameter of approximately 125 microns to 1 mm is typical.

[0041] The notch 34 contains a luminescent material 36, such as aphosphor or fluorescent material. The notch 34 may be left open orfilled in with a filling material 38. The filling material 38 could be atypical optical filler substance known in the art, or it could be aluminescent material. Filling in the notch results in a strongerstructure and enhanced optical properties. The depth of the notch canvary. If multiple notches are provided on a single optical fiber and alight, e.g. radiation, source is provided from only one side, the depthof each notch 34 can be increased as the notches are located furtherfrom the light source. This allows for equal illumination of each notch,even though some notches are further from the light source. The notch 34is shown in the shape of a right triangle, but can be formed at avariety of angles. Also, the notch 34 can be a narrow slit, just wideenough for the luminescent material 36 to be deposited. Although onlyone notch is shown, a plurality of notches may be formed in the opticalfiber 32. The notches do not necessarily need to be oriented in the samedirection; they may be formed to face multiple directions.

[0042] If, as is preferred, phosphor is used as the luminescent material36, the phosphor thickness is approximately typically 50 to 100 micronsThe luminescent material 36 may be mounted as shown in FIG. 1, or on theoutside edge of a notch 34 containing filling material 38, or may be acoating large enough to cover both the outside edge of the optical fiber32 and fill in the notch 34, or transversally-opposite side of theoptical fiber 32 from the notch 34, similar to the location of thereflective coating 42 shown in FIG. 1. The luminescent material 36 canalso be formed as a sheet, providing for easier application to multipleoptical fibers.

[0043] Ideally, a dichroic filter 40 is located between the luminescentmaterial 36 and the optical fiber 32. The dichroic filter 40 allowsinfrared (IR) light to pass, but reflects visible light. Also, areflective coating 42 may be mounted on the optical fiber 32transversally opposite from the notch 34. The reflective coating 42reflects all types of radiation. Both IR and visible light are reflectedby reflective coating 42 as shown in FIG. 1.

[0044] The operation of the optical luminescent display device 30 is asfollows. Radiation is provided through the optical fiber 32 so that itcommunicates with the luminescent material 36, causing the luminescentmaterial 36 to emit visible light. Visible light is then projected fromthe luminescent material 36. If present, the dichroic filter 40 and thereflective coating 42 each serve to enhance the visible light emittingfrom the luminescent material 36 so as to brighten the display. Thedichroic filter 40 reflects visible light and therefore reflects thevisible light emitted by the luminescent material 36 outward and helpsto keep the visible light out of the optical fiber 32. The reflectivecoating 42 reflects radiation passing through the optical fiber 32, suchas IR light, ultraviolet (UV) light, or visible light that may bedeflected downward by the notch 34. As shown in FIG. 1, the reflectivecoating 42 reflects any radiation, such as IR light back in thedirection of the notch 34 to enhance the amount of radiation reachingthe luminescent material 36. Visible light emitted by the luminescentmaterial is similarly reflected so as to enhance the amount of visiblelight emitted in the direction of the viewer.

[0045] Phosphorescence is the emission of light from certain inorganicmaterials following excitation by photons, electrons, or high-energyradiation. Absorption of the incident radiation occurs becausevalence-band electrons in the material are excited to higher-energystates. In normal materials and in fluorescent substances the excitedelectron returns quickly to the ground state, and emission of lightdecays very soon after cessation of the incident, i.e. exciting,radiation. In phosphorescent materials, in contrast, the decay of theexcited state is prolonged, often because the excited electrons aretrapped at acceptor states just below the conduction band.

[0046] The radiation provided through the optical fiber 32 may be IRlight, UV light, visible light, or any radiation or energy that servesto cause the luminescent material 36 to emit visible light. In oneembodiment, the luminescent material 36 is double illumination, i.e.co-incident, luminescent material and does not emit visible light untiltwo wavelengths of light communicate with it. As shown in FIG. 1, UVlight 44 is radiated from one direction and IR light 46 is radiated fromanother direction.

[0047] The UV light 44 is typically of a wavelength approximately of 200to 380 nm. The IR light 46 is typically of a wavelength approximately of700 to 1380 nm. Optionally, the direction from which the light isradiated may be reversed or radiated from the same side. Otherluminescent material 36, which is single illumination luminescentmaterial, only requires one wavelength of light to communicate with itto cause it to emit visible light.

[0048] The operation of an example of a phosphor, such as SmEu, is asfollows. Eu++ has a 4 f ground state just above the valence band of thelattice, and a 5 d excited state just below the conduction band. Blue orUV light, depending on the composition of the phosphor, excites the Eu++ion to the 4 d state. Sm++ creates traps just below the conduction bandin these materials. By a charge-transfer mechanism, the excited Eu++electron is quickly transferred to a Sm+++ trap. The trap state is morethan 1 eV below the conduction band and quite stable. Formally, the Eu++becomes Eu+++ (Eu++ with a bound hole) and the Sm+++ becomes Sm++ via acharge-transfer reaction. In this state the phosphor is primed.Irradiating the phosphor with IR light of 980 nm, although 1.1 μm or sois best, kicks electrons out of the Sm traps and allows them to fallback into the Eu 5 d excited state. The Eu 5 d to 4 f transition back tothe ground state produces visible light emission peaking at about 640nm; the difference between the wavelengths of the excitation andemission maxima is due to Stokes shift. The maximum amount of lightwhich can be liberated during photostimulation is limited only bysaturation of the Sm co-activator sites.

[0049] In double illumination phosphors, the process of excitationproceeds by a two-step mechanism: incident light of one wavelength,typically blue or UV, excites electrons directly to the conduction bandand these electrons quickly migrate to acceptor states or ‘traps’ withenergy somewhat below the conduction band. These states have arelatively long lifetime. The phosphor is said to be ‘sensitized’ when asignificant fraction of these acceptor states are occupied. Subsequentirradiation of such a sensitized phosphor with light of a secondwavelength, often red or IR wavelength, can induce transitions from theacceptor states to higher-energy states which decay by normalphosphorescence.

[0050] At present, the two most common storage phosphors have broad bandemission at 520 nm and 650 nm and are intended for monochromaticapplication.

[0051] The spectrum of the visible light emitted by individual phosphorelements can be tailored chemically, or by the use of superposed opticalfilters, permitting a full-color display to be realized. FIGS. 2-4illustrate the ability to change the color of the visible light emittedby a double illumination phosphor by adjusting the amount of radiationof IR light or UV light within various frequency bands. For example, asshown in FIG. 2, with sensitizing UV radiation between 200 and 380 nmand using a EuSm phosphor, blue light is emitted if IR light ofapproximately between 700 and 780 nm is supplied. Green light is emittedif IR light of approximately between 830 and 900 nm is supplied. Redlight is emitted if IR light of approximately between 980 and 1180 nm issupplied.

[0052]FIG. 4 illustrates that with sensitizing IR radiation between 700and 1380 nm, using a EuSm phosphor, blue light is emitted if UV light ofapproximately 255 nm is supplied. Green light is emitted if UV light ofapproximately 302 nm is supplied. Red light is emitted if UV light ofapproximately 365 nm is supplied.

[0053] Conventional rare earth dopants such as thulium, cerium, europiumand samarium can be utilized to adjust the color emitted by a phosphor.In general, these phosphors possess a nanosecond rise time, and decaytimes that vary from nanoseconds to milliseconds. Thus, there issufficient control over phosphorescence for optimization of displaytimes and rapid readout technologies. Therefore, the alkaline earthmaterials are suitable for application to optical switching technologiesand the next generation of flat panel display materials.

[0054]FIG. 5 illustrates another variation of the optical luminescentdisplay device 30. This variation is intended to provide radiation 50 inthe optical fiber 32 from one direction. The radiation 50 can be anytype of radiation that will cause the single-illumination luminescentmaterial 36 to emit the desired radiation wavelength. If the luminescentmaterial 36 is a phosphor, UV light of 200-380 nm or IR light of700-1380 nm can be used to cause the luminescent material 36 to emitvisible light. For example, to produce red, YVO₄:Eu or3.5MgO·0.5MgF_(2·GeO) ₂:Mn phosphors can be used. To produce green,Zh·Ge·O·Mn phosphor can be used. To produce blue, (SrCaBa)₅(PO₄)₃Cl:Euphosphor can be used. The above listed phosphors are activated by UVlight between 200-380 nm, ideally 365 nm., and are commerciallyavailable from Nichia Chemical Industries, Ltd., part numbers NP-312,NP-320, NP-202, NP-105, respectively. The notch 34 is provided with amirror coating 48 to enhance the amount of radiation provided to theluminescent material 36 and reduce the amount of visible light emittedby the luminescent material 36 entering the optical fiber 32.

[0055] Optical Switch

[0056] Another embodiment of the invention involves an optical switch.An optical switch device 60 is shown in FIG. 6. An optical luminescentdisplay device 30 is provided with a luminescent material 36 and one ormore optical pickups 62. A dichroic filter 40 is optional. Theluminescent material 36 is a double illumination luminescent material,requiring two types of radiation to emit visible light. The opticalswitch device 60 is activated when both types of radiation are providedwithin the optical fiber 32 to cause the luminescent material 36 to emitvisible light. For example, when both UV light 44 and IR light 46 areprovided, a luminescent material 36, such as a phosphor, will emitvisible light. The optical pick up 62, which may be accompanied byanother optical pick up 62, pick up the visible light to provide theswitch output to the desired location.

[0057] Another variation of an optical switch is shown in FIG. 7. UVlight 44 is radiated within the optical fiber 32 from either direction.An optical switch 90 is formed from a laser diode 92 arranged to provideIR light to a luminescent material 36 located in or near notch 34 ofoptical fiber 32. UV light 44 is provided within the optical fiber 32.To activate the optical switch 90, the laser diode 92 is activated,thereby providing IR light to the luminescent material 36. Theluminescent material 36 is a double illumination luminescent material,requiring two types of radiation to emit visible light. UV light 44 isalready provided in the optical fiber 32. Therefore, when the laserdiode 92 provides IR light, the luminescent material 36 emits visiblelight. This visible light communicates with the optical pickup 62,providing a modulated visible light output. To avoid multipleluminescent materials 36 emitting visible light when only one laserdiode 92 is activated, the optical switches 90 can be spaced far apart.Ideally, each optical switch 90 is formed from a luminescent material 36activated by a different frequency of IR light than that of nearbyoptical switches 90. Therefore, a corresponding frequency laser diode 92is used to activate the luminescent material 36 in each optical switch90, allowing closer spacing of the optical switches 90. Optionally, anIR LED can be used in place of the laser diode 92.

[0058] It is understood that both embodiments of the optical switch canbe operated using radiation types other than discussed above, such asvisible light or any energy capable of causing the luminescent material36 to emit the desired radiation. A luminescent material 36 to provide anon-visible output, such as IR, for example, may also be used. Also, IRand UV radiation can be reversed in the descriptions above.

[0059] Optical Display Panel

[0060] Another embodiment of the invention involves a matrix of opticalfibers to form an optical display panel. FIGS. 17 and 23-26 illustrateexamples of such a matrix configuration. FIGS. 8-14 provide a variety ofexamples of the structure that can be used for each pixel of the opticaldisplay panel. FIGS. 23-25 are perspective views of examples of thestructure of an optical display panel. FIG. 26 illustrates an opticaldisplay panel with detailed structural elements omitted for clarity.

[0061] A double illumination luminescent material can be used as thebasis for a coincidentally-addressed optical display panel.Side-emitting optical fibers (T. Wang et al., U.S. Pat. No. 5,673,344)are ideally-suited to provide coincident illumination of the luminescentpixel elements in a display of this type, as seen in FIGS. 8-14 and 24.

[0062] U.S. Pat. No. 190 5,673,344 is incorporated herein by referencein its entirety. One optical fiber in these figures delivers‘sensitizing’ (typically blue or UV wavelength) radiation to one row ofphosphor pixels at a time, while another fiber delivers secondaryexciting radiation (typically red or IR) to each column of phosphorpixels.

[0063] Pixel elements which receive either (i) ‘sensitizing’ radiationonly or (ii) ‘secondary’ radiation only do not emit light. With only asingle horizontal fiber and a single vertical fiber active, only thepixel at the intersection of these fibers will radiate light. By thewell-known method of sequential activation or time-multiplexing of thehorizontal and vertical fibers, an image may be displayed.

[0064] As shown in FIG. 8, two optical fibers 32 are used to provideradiation to a luminescent material 36. For a double illuminationluminescent material, UV light 44 is provided by one optical fiber 32 tosensitize the luminescent material 36, located between the opticalfibers 32. To cause the luminescent material 36, to emit visible light,IR light 46 is provided by the other optical fiber 32. Ideally, a mirror48 may be used to increase the amount of UV light 44 that reaches theluminescent material 36 and reduce the amount of visible light emittedby the luminescent material entering the optical fiber 32 having themirror 48. A mirror 48 is not used on the other optical fiber 32 becausethe visible light shines through this optical fiber 32 for viewing. Thedirection of viewing of the device in FIG. 8 is shown by arrow A.

[0065] Although UV light 46 and IR light 44 are described above, anyradiation can be used that will cause the luminescent material 36 toemit the desired wavelength of radiation, such as visible light.

[0066]FIG. 9 shows a structure similar to that shown in FIG. 8, exceptthat, by way of example, a different position of the luminescentmaterial 36 is shown. The notch 34 containing luminescent material 36contains a filling material 38 so as to hold the luminescent material 36in place. Other possibilities are available for the location ofluminescent material 36. For example, luminescent material 36 may belocated in one of the notches 34 at an angle or parallel to the axis ofthe optical fibers 32.

[0067]FIG. 10 shows a structure similar to that shown in FIG. 8, exceptthat, by way of example, a different notch 152 configuration is shown. Avariety of combinations of notch shape and location are possible. FIG.11 adds reflective filter 154. The reflective filter 154 can beconfigured to allow UV light 44 to pass, but reflect visible light. Thiswould enhance the visible light emitted from the luminescent material 36in the direction of the viewer. The direction of viewing is shown byarrow A. Notch 152 may be open or filled with filling material 38.

[0068]FIG. 12 involves a notch 182 containing a reflection pyramid 190.The reflection pyramid 190 is ideally formed with its peak set in fromthe edge of the optical fiber 32, to distribute radiation to theluminescent material 36, as shown by the exemplary small arrows,regardless of the direction from which the radiation is provided. Thereflection pyramid 190 can be inserted into the notch 182, or the notch182 can be formed with an inner edge forming a reflection pyramid 190.The area 192 within the notch 182 may be left open or, preferably,filled with a filling material. The optional dichroic filter 186increases the amount of IR light 46 and discharge UV light 188 directedtoward the luminescent material 36. However, visible light is allowed topass through to the viewer, who is viewing in the direction of the arrowA. Discharge UV light 188 is provided to adjust the charge within theluminescent material 36. The discharge UV light 188, at a wavelength ofbetween 200 and 380 nm, increases the charge of the luminescent material36 so as to prevent or discontinue the emission of visible light fromthe luminescent material 36. This, in essence, restarts thesensitizing/excitation process for the luminescent material 36. Anotherprocess of applying UV light 44 can be followed by IR light 46 to resultin the emission of visible light by the luminescent material 36. SeeFIGS. 21 and 22 as examples of timing charts that could be used in theapplication of discharge UV light 188, IR light 46, and UV light 44. Thetiming of FIG. 22 is preferred over that of FIG. 21, because the UVlight has time to sensitize the luminescent material prior to theapplication of the exciting IR light.

[0069] If the luminescent material 36 does not possess, or has veryshort, memory properties, a discharge UV light 188 may not be necessary.In such a case, the emission of visible light would cease upon either UVlight 44 or IR light 46 not being provided.

[0070]FIG. 13 shows notches 212 formed on the outer sides of the opticalfibers 32. FIG. 14 adds a dichroic filter 186. The dichroic filter 186reflects UV light and IR light, but allows visible light to pass. Thedichroic filter 186 increases the amount of IR light 46 and discharge UVlight 188 directed toward the luminescent material 36. However, visiblelight is allowed to pass to the viewer, who is viewing in the directionof the arrow A. FIG. 14 shows the preferred location and orientation ofthe notches 212 with respect to the luminescent material 36 for theoptical display panel of the invention.

[0071] Although FIGS. 8-14 show the fibers as parallel, the fibers canbe perpendicular as shown in FIGS. 17, and 23-26, or at any angle.Parallel orientation is the least desirable orientation, as a row andcolumn configuration can not be established with all the optical fibersoriented in the same direction, thereby frustrating individual pixeladdressing.

[0072] To form an optical display panel to display images in color, twotypes of luminescent materials can be used. Multi-color luminescentmaterials can be used such that the color of each pixel of luminescentmaterial is adjusted by providing the proper wavelength of sensitizingand/or exciting radiation. Alternatively, single-color luminescentmaterials can be used. FIGS. 15 and 16 show examples of single-colorpixel configurations.

[0073]FIG. 15 illustrates a standard pixel layout 300 with red pixels302, green pixels 304 and blue pixels 306 arranged in row or columnorder. Ideally, the pitch will be 1.0 mm and the pixel width 0.95 mm,but these can be adjusted for various optical fiber diameters. Toenhance the crispness of the image displayed by the screen, the pixelcolor groups should be arranged diagonally, as shown in FIG. 16. Redpixels 332, green pixels 334 and blue pixels 336 are shown in apreferred pixel layout 330. “R” “G” and “B” are shown in FIGS. 15 and 16for illustrative purposes only. An optional black mask 338 is shownformed between each pixel. Use of the black mask 338 is preferable toenhance the clarity of the image displayed.

[0074] A phosphor, BaFBr:Eu²⁺, can be used for a red pixel that willilluminate upon exposure to both UV and IR light. The phosphorsSrS:Ce:Sm or SrS:Eu:Sm can be used for a green pixel that willilluminate upon exposure to both UV and IR light. A phosphor,Ba₃(PO₄)₂:Eu²⁺,La³⁺, can be used for a blue pixel that will illuminateupon exposure to both UV and IR light.

[0075] A perpendicular matrix 360 is shown in FIG. 17. A pixel 370, asection or piece of luminescent material analogous to luminescentmaterial 36, is addressed by radiation provided to the optical fibers372 and 374. As described with relation to FIGS. 12-14, the pixel 370,analogous to luminescent material 36, is provided with UV light, from aUV source 368, IR light, from an IR light source 366, and UV dischargelight, from a UV discharge source 364. Each of these light or dischargesources is directed via an addressing means 362 that selects one fiberper axis. For example, the proper optical fiber 372 is selected fromamong the rows or the proper optical fiber 374 from among the columns.The sources can be arranged to provide radiation from the same end ofthe fiber. For example, a UV discharge source 364 can be supplied fromthe same fiber end as the IR source 366. It is also possible to use onesource per axis and adjust the wavelength of the output to the type oflight required.

[0076] Although luminescent material, such as phosphor, can be depositeddirectly on the optical fibers by using processes such as printing,coating or sputtering, alternatively, a phosphor plate 398, shown inFIG. 18, can be used. The phosphor plate 398 can be formed using asubstrate, typically glass, although plastic is also suitable. Powderedphosphor is deposited upon the substrate. The powder can be depositedusing processes such as printing, coating or sputtering. The substratecan be opaque, requiring radiation to be provided to the phosphor fromthe same side of the substrate as the phosphor. Alternatively, atransparent or translucent substrate may be used to allow radiation tobe provided from both sides of the substrate. The preferred substratefor the optical display panel, shown in FIG. 18, is transparent. Asecond type of phosphor plate 398 involves a phosphor film, availablecommercially, wherein the phosphor is mounted to a film.

[0077]FIG. 18 illustrates another embodiment of the optical displaypanel 390 from a side view. The optical display panel 390 is viewed inthe direction of arrow A. In this embodiment the optical fiber 392provides IR light and the optical fiber 394 provides UV light to asection of a phosphor plate 398 disposed between the optical fibers 392and 394. This section of the phosphor plate 398 functions as a pixel 400of the optical display panel. A discharge lamp 396 is provided at therear of the display to provide discharge radiation from outside theoptical fibers. In this embodiment, the optical fiber 392 providing IRlight and the optical fiber 394 providing UV light do not need to alsoprovide discharge radiation, as it is provided by discharge lamp 396.The discharge radiation passes transversally through the optical fiber394 to the phosphor plate 398. To reduce the thickness of the display,the discharge lamp 396 can illumine the phosphor plate 398 by way of aside-emitting optical fiber.

[0078] The phosphor plate 398 can use a standard pixel layout 300, asshown in FIG. 15, or a preferred pixel layout 330 of FIG. 16.Alternatively, the phosphor plate 398 can be formed of multi-colorluminescent material.

[0079] FIGS. 23-26 provide perspective views of an example of an opticaldisplay panel. FIGS. 23 and 26 show an overall configuration of theoptical display panel. FIG. 26, while omitting detailed structural itemsfor clarity, illustrates the principle of providing radiation tointersecting optical fibers 32 to illuminate the pixel 512 at theintersection of the optical fibers 32.

[0080] FIGS. 23-25 illustrate a phosphor plate 398 mounted betweenoptical fibers 32 arranged to have notches 34 located at theintersections of the optical fibers 32. A luminescent material 36 ismounted between the notches 34. Optionally, the spacing of the opticalfibers 32 oriented in the same direction can be increased or decreased.Although the luminescent material 36 is illustrated as individualpieces, one for each optical fiber 32 intersection, it is also possibleto provide luminescent material 36 large enough to be mounted betweenmultiple optical fiber 32 intersections, even covering the entirephosphor plate 398. In such a case, masking, such as black mask 338,discussed above in relation to FIGS. 15 and 16, is preferred. FIGS.23-25 are progressive magnifications of the same example of an opticaldisplay panel.

[0081] The ability to select the proper row and column so that theirintersection is located at the desired location in the matrix is knownin the art. The direction of the proper wavelengths of light into eachof two optical fibers, such that the intersection of the two fibersoccurs at the desired location in the optical display panel, may beperformed using structures similar to those shown FIGS. 19-20C. FIG. 19illustrates a radiation direction assembly 420. Radiation is provided bythe laser array 422. The laser array 422 could produce UV light or IRlight, or could be substituted with another radiation producing device.Ideally, the laser array 422 has an output of 30 to 40 W, but may alsobe of greater or lesser power. The lens array 424 focuses the radiationemitted from the laser array 422. The optical beam switch 426 directsthe radiation to the proper optical fiber within the optical fiberbundle 430. Discharge radiation, capable of illuminating all the opticalfibers within the optical fiber bundle 430 simultaneously, is providedby a discharge light source 434. The discharge radiation is providedthrough a lens 432 into a beam splitter 428. The beam splitter isarranged to provide radiation to multiple optical fibers within theoptical fiber bundle 430.

[0082] Ideally, a radiation direction assembly 450 can be used. FIGS.20A and 20C illustrate this embodiment. In the radiation directionassembly 450, a linear laser array 452 is used to provide a plurality ofradiation sources. Ideally, each of the emitters within the laser array452 has an output of 30 to 40 W, but may also be of greater or lesserpower. A lens array 454 and an optical beam switch 456 are also providedto focus and direct the radiation, respectively. The optical fiberbundle 458 can best be arranged, as shown by way of example in FIG. 20B,such that the optical fibers that make up the columns of the opticaldisplay panel and optical fibers that make up the rows of the opticaldisplay panel are provided in one bundle. This allows the opticaldisplay panel to be operated from a single optical fiber bundle 458 anda single radiation direction assembly 450, if desired. Alternatively, aradiation direction assembly 450 can be provided for each axis of theoptical display panel.

[0083] It is understood that multiple optical display panels can be usedin close proximity to each other, each displaying only a portion of theentire desired image. Such a configuration allows for lower poweredradiation sources and the use of luminescent materials with slowerresponse times, e.g. requiring longer application times forsensitization, excitation, or discharge radiation.

[0084] Single illumination luminescent material, e.g., requiring onlyone type of radiation to cause it to emit visible light, may also beused as the basis for an optical display panel. A luminescent materialpossessing a logarithmic relationship between absorbed radiation andemitted visible light, as well as poor storage properties, would be mostbeneficial.

[0085] In photostimulable phosphors, typically known as ‘ordinary’phosphors, electrons are excited by blue or UV light, electronbombardment in a CRT, or absorption of X-ray or other radiation andreturn slowly to the ground state, producing a sustained butslowly-decaying ‘phosphorescence’ after the exciting source is turnedoff. In phosphors of the type discussed below, however, the emission oflight decays very quickly after the exciting source is turned off. Thephosphor, however, remains in an activated, e.g. sensitized, state, andshining long-wavelength light on the phosphor while it is in theactivated state will cause the phosphor to emit visible light. In thedark, the activated state of the phosphor may persist for quite a longtime days or even weeks.

[0086] Most phosphors consist of trace quantities of so-called‘activator’ or ‘co-activator’ substances distributed in a host lattice.In the case of the photostimulable phosphors discussed here, the hostlattice is a wide-bandgap II-VI material, typically in alkaline-earthsulfide (MgS, CaS, or SrS). The ‘activator’ species is typicallyeuropium (as Eu++) and the ‘co-activator’ species is typically samarium(as Sm+++), both present at about 100 ppm concentration. These are addedas chloride salts, and some of the chloride ion enters the lattice. Clsubstituting for S— is believed to compensate the charge excess of Sm+++substituting for M++ metal ion. The compositions are designated as host:(activators), e.g., SrS: (Sm, Eu).

[0087] By way of example, consider a 15″ optical display panel with adisplay area of about 700 cm^ 2. If 1 W of blue photons are available toexcite the phosphor, and the overall efficiency of excitation is 50%,then a surface brightness of a few hundred mLambert is likely achievableat somewhat greater than the typical brightness of a CRT display,requiring an IR flux of nearly 10 W.

[0088] Regarding specific storage phosphors with RGB characteristics fordisplay applications, the generic phosphors include alkaline earthchalcogenides. Typical phosphors of this type include magnesium,calcium, strontium and barium sulfides. They are activated andsensitized with co-dopants which can trap electrons at shallow levelsbelow the conduction band with subsequent infrared stimulation inducingradiative recombination processes, i.e., emission of light. Typically,these storage phosphor materials have not found application in displayapplications. However, singly-doped materials have been used inelectroluminescent display applications.

[0089] The display panel of the present invention is entirely opticaland can be separate from the light sources, such as laser, LED or lamp,providing excitation. The display panel may connect to theelectro-optical module via a flexible fiber optics cable. Because it isall-optical, a display panel of this type is expected to be especiallyrugged and will be able to operate in certain environments whereelectronic devices cannot be used. Also, the display panel will not haveelectronics part built in, such as TFT transistor, pixel drivers,electrode and line or column electrical wire. There is no high-voltage,no electromagnetic radiation, no EMI from the display panel. Due to thesimple construction of a display panel of this type, the cost ofmanufacture is expected to be significantly lower than that ofcompetitive display technologies.

[0090] The present invention has been described by way of example, andmodifications and variations of the exemplary embodiments will suggestthemselves to skilled artisans in this field without departing from thespirit of the invention. The preferred embodiments are merelyillustrative and should not be considered restrictive in any way. Thescope of the invention is to be measured by the appended claims, ratherthan the preceding description, and all variations and equivalents whichfall within the range of the claims are intended to be embraced therein.

What is claimed is:
 1. An optical fiber containing a notch, wherein saidnotch is configured so as to direct radiation energy within the fibertoward a luminescent material.
 2. An optical luminescent display device,comprising: a luminescent material; and side emitting optical fibermeans adapted for supplying radiant energy to said luminescent material.3. An optical luminescent display device, adapted for use with a radiantenergy source, comprising: an optical fiber; a luminescent material; anda notch formed in said optical fiber adapted to direct a first type ofradiant energy within said optical fiber toward said luminescentmaterial.
 4. An optical luminescent display device of claim 3, furthercomprising: a reflective coating mounted on said optical fibertransversally opposite from said notch.
 5. An optical luminescentdisplay device of claim 3, wherein: said luminescent material requiresexcitement from a first type of radiant energy to emit visible light. 6.An optical luminescent display device of claim 3, wherein: saidluminescent material requires excitement from a first type of radiantenergy and a second type of radiant energy to emit visible light.
 7. Anoptical luminescent display device of claim 6, wherein: said luminescentmaterial is a phosphor.
 8. An optical luminescent display device ofclaim 6, further comprising: a second optical fiber; and a second notchformed in said second optical fiber adapted to direct said second typeof radiant energy toward said luminescent material.
 9. An opticalluminescent display device of claim 8, further comprising: a dischargelamp adapted to provide radiation to said luminescent material bytransversally penetrating at least one of the group of said opticalfiber and said second optical fiber; wherein said discharge lamp islocated external to said optical fiber and said second optical fiber.10. An optical luminescent display device of claim 8, wherein: saidoptical fiber and said second optical fiber are formed of plastic. 11.An optical luminescent display device of claim 8, wherein: said opticalfiber and said second optical fiber are formed of glass.
 12. An opticalluminescent display device of claim 8, wherein: said notch and saidsecond notch are filled.
 13. An optical luminescent display device ofclaim 8, wherein: said luminescent material is a phosphor.
 14. Anoptical luminescent display device of claim 13, wherein: said first typeof radiant energy is UV light; and said second type of radiant energy isIR light.
 15. An optical luminescent display device of claim 14,wherein: wavelengths of said first type of radiant energy and saidsecond type of radiant energy can be adjusted to adjust the color ofvisible light emitted from said luminescent material.
 16. An opticalluminescent display device of claim 14, further comprising: a dichroicfilter formed between said luminescent material and said optical fiber.17. An optical luminescent display device of claim 14, furthercomprising: a mirror coating formed in said notch.
 18. An opticalluminescent display device of claim 14, wherein: said luminescentmaterial is a phosphor consisting essentially of EuSm.
 19. An opticalluminescent display device, comprising: an optical fiber; a luminescentmaterial; and means for deviating a path of radiation travelling withinsaid optical fiber away from the axis of said optical fiber toward saidluminescent material.
 20. A method for causing a luminescent material toemit visible light, comprising: an optical fiber; a radiant energysource emitting radiant energy into said optical fiber; and aluminescent material capable of emitting visible light when radiated bysaid radiant energy; a notch formed in said optical fiber adapted todirect said radiant energy within said optical fiber toward saidluminescent material.
 21. An optical display panel, comprising: aplurality of first optical fibers arranged to have common axialorientation; a second optical fiber arranged so as not to be parallel tosaid plurality of first optical fibers; a luminescent material locatedbetween said plurality of first optical fibers and said second opticalfiber; notches formed in said plurality of first optical fibers toprovide side-emission of radiation directed toward said luminescentmaterial; and corresponding notches in said second optical fiber toprovide side-emission of radiation directed toward said luminescentmaterial.
 22. An optical display panel of claim 21, wherein: saidluminescent material is formed as a plurality of individual pixels. 23.An optical display panel of claim 21, wherein: said notches are formedon the outer side of said plurality of first optical fibers; and saidcorresponding notches are formed on the outer side of said secondoptical fiber.
 24. An optical display panel of claim 21, wherein: saidnotches are formed on the inner side of said plurality of first opticalfibers; and said corresponding notches are formed on the inner side ofsaid second optical fiber.
 25. An optical display panel of claim 21,wherein: said notches and said corresponding notches are filled.
 26. Anoptical display panel of claim 21, wherein: said luminescent material islocated in said notches.
 27. An optical display panel of claim 21,further comprising: a reflective coating mounted on said optical fibertransversally opposite from said notches.
 28. An optical display panelof claim 21, wherein: said luminescent material requires excitement froma first type of radiant energy to emit visible light.
 29. An opticaldisplay panel of claim 21, wherein: said luminescent material requiresexcitement from a first type of radiant energy and a second type ofradiant energy to emit visible light.
 30. An optical display panel ofclaim 29, wherein: said luminescent material is a phosphor.
 31. Anoptical display panel of claim 30, wherein: said first type of radiantenergy is UV light; and said second type of radiant energy is IR light.32. An optical display panel of claim 31, wherein: wavelengths of saidfirst type of radiant energy and said second type of radiant energy canbe adjusted to adjust the color of visible light emitted from saidluminescent material.
 33. An optical display panel of claim 31, furthercomprising a dichroic filter formed between said luminescent materialand said optical fiber.
 34. An optical display panel of claim 31,further comprising: a mirror coating formed in said notch.
 35. Anoptical display panel of claim 31, wherein: said notches and saidcorresponding notches are filled.
 36. An optical display panel of claim31, wherein: said luminescent material is a phosphor consistingessentially of EuSm.
 37. An optical display panel of claim 21, furthercomprising: a discharge lamp adapted to provide radiation to saidluminescent material by transversally penetrating at least one of thegroup of said plurality of first optical fibers and said second opticalfiber; wherein said discharge lamp is located external to said pluralityof first optical fibers and said second optical fiber.
 38. An opticaldisplay panel of claim 21, wherein: said plurality of first opticalfibers and said second optical fiber are formed of plastic.
 39. Anoptical display panel of claim 21, wherein: said plurality of firstoptical fibers and said second optical fiber are formed of glass.
 40. Anoptical display panel, comprising: a plurality of first optical fibersarranged to have common axial orientation; a second optical fiberarranged so as not to be parallel to said plurality of first opticalfibers; a luminescent material located between said plurality of firstoptical fibers and said second optical fiber; means for deviating a pathof radiation travelling within said plurality of first optical fibersaway from the axis of each of said plurality of first optical fiberstoward said luminescent material; and means for deviating a path ofradiation travelling within said second optical fiber away from the axisof said second optical fiber toward said luminescent material.
 41. Amethod for operating an optical display panel, comprising: a pluralityof first optical fibers arranged to have common axial orientation; asecond optical fiber arranged so as not to be parallel to said pluralityof first optical fibers; a radiant energy source emitting a firstradiant energy into one of said plurality of first optical fibers; aradiant energy source emitting a second radiant energy into said secondoptical fiber; and a luminescent material capable of emitting visiblelight when radiated by said first radiant energy and said second radiantenergy; notches formed in said plurality of first optical fibers toprovide side-emission of radiation directed toward said luminescentmaterial; and corresponding notches in said second optical fiber toprovide side-emission of radiation directed toward said luminescentmaterial. wherein said luminescent material is located between saidplurality of first optical fibers and said second optical fiber.
 42. Amethod for operating an optical display panel as in claim 41, furthercomprising: matrix addressing means.
 43. An optical switch, comprising:an optical fiber; a luminescent material; a notch formed in said opticalfiber adapted to direct a first type of radiant energy within saidoptical fiber toward said luminescent material; and an optical pickupfor optical communication with said luminescent material.
 44. An opticalswitch, comprising: an optical fiber; a luminescent material requiringexcitement from a first type of radiant energy and a second type ofradiant energy to emit visible light; a notch formed in said opticalfiber adapted to direct a first type of radiant energy within saidoptical fiber toward said luminescent material; and a laser diode ableto radiate said luminescent material with a second type of radiantenergy.
 45. An optical switch as in claim 44, further comprising: anoptical pickup for optical communication with said luminescent material.46. An optical switch as in claim 44, wherein: said first type ofradiant energy is UV light; and said second type of radiant energy is IRlight.
 47. An optical switch as in claim 44, further comprising: asecond luminescent material requiring excitement from said first type ofradiant energy and a third type of radiant energy to emit visible light;a second notch formed in said optical fiber adapted to direct said firsttype of radiant energy within said optical fiber toward said secondluminescent material; and a second laser diode adapted to radiate saidsecond luminescent material with a third type of radiant energy.
 48. Anoptical switch as in claim 44, wherein: said notch is filled.